The effect of nickel on the structure, mechanical and technological properties of a high-strength casting Al-6%Zn-2%Mg-1% Cu-0.15%Cr alloy was studied. The most favorable combination of properties (170-200 HB, UTS= 530-600 MPa, El = 3-9%) is shown to be attained at 4% Ni; it is consistent with the results of analysis of the phase diagram of the AI-Zn-Mg-Cu-Ni system, some fragments of which are constructed in the present work. An alloy with 4% Ni is greatly superior to a high-strength alloy of AA7075 type in technological efficiency for casting. This concerns primarily the lesser tendency to form hot cracks in castings and the possibility of producing welded joints by argon-arc welding.